I've been using an ozonizer for about a month with an ORP controller. I have a 135 gallon reef with a 70 gallon sump. I am using a 100 mg unit. In two days, I had the clearest water I have ever had by far.

It definitely dropped my skimmer production - it's about 1/2 of what it used to be, but the tank is definitely cleaner and clearer. I had always run carbon in a fluidized reactor, but always had that slight yellow tinge that I could not seem to get rid of. It's all gone now.

I have seen no negatives so far, and it's relatively maintenance free (except for the air dryer). I would definitely recommend it.